8XC251SA, SB, SP, SQ USER’S MANUAL

Example: Eight-bit register Rm contains 055H (01010101B) and the 16-bit register WRj contains 0FFFFH (11111111 11111111B). The instruction

MOVS WRj,Rm

moves the contents of register Rm (01010101B) to register WRj (i.e., WRj contains 00000000 01010101B).

Variations

MOVS WRj,Rm

Binary Mode Source Mode

Bytes:

States:

[Encoding]

Hex Code in:

Operation:

32

21

0 0 0 1

1 0 1 0

 

 

Binary Mode = [A5][Encoding] Source Mode = [Encoding]

MOVS

(WRj).7–0 ← (Rm).7–0

(WRj).15–8 ← MSB

t t t t

s s s s

MOVX <dest>,<src>

Function:

Move external

Description: Transfers data between the accumulator and a byte in external data RAM. There are two types of instructions. One provides an 8-bit indirect address to external data RAM; the second provides a 16-bit indirect address to external data RAM.

In the first type of MOVX instruction, the contents of R0 or R1 in the current register bank provides an 8-bit address on port 0. Eight bits are sufficient for external I/O expansion decoding or for a relatively small RAM array. For larger arrays, any port pins can be used to output higher address bits. These pins would be controlled by an output instruction preceding the MOVX.

In the second type of MOVX instruction, the data pointer generates a 16-bit address. Port 2 outputs the upper eight address bits (from DPH) while port 0 outputs the lower eight address bits (from DPL).

For both types of moves in nonpage mode, the data is multiplexed with the lower address bits on port 0. In page mode, the data is multiplexed with the contents of P2 on port 2 (8-bit address) or with the upper address bits on port 2 (16-bit address).

It is possible in some situations to mix the two MOVX types. A large RAM array with its upper address lines driven by P2 can be addressed via the data pointer, or with code to output upper address bits to P2 followed by a MOVX instruction using R0 or R1.

Flags:

CY

AC

OV

N

Z

 

 

 

 

 

—

—

—

—

—

 

 

 

 

 

A-98

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Intel 8XC251SA, 8XC251SP, 8XC251SQ, 8XC251SB, Embedded Microcontroller manual Movs, Movx dest,src Function
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Embedded Microcontroller, 8XC251SP, 8XC251SA, 8XC251SQ, 8XC251SB specifications

The Intel 8XC251 series of embedded microcontrollers is a family of versatile and powerful devices, designed to meet the demands of a wide range of applications. With models such as the 8XC251SB, 8XC251SQ, 8XC251SA, and 8XC251SP, this series offers unique features while maintaining a high level of performance and reliability.

At the heart of the 8XC251 microcontrollers is the 8051 architecture, which provides a 16-bit processor capable of executing complex instructions efficiently. This architecture not only allows for a rich instruction set but also facilitates programming in assembly language and higher-level languages like C, which are essential for developing sophisticated embedded systems.

One of the significant features of the 8XC251 family is its integrated peripherals, including timer/counters, serial communication interfaces, and interrupt systems. These peripherals enable developers to implement timing functions, data communication, and real-time processing, all of which are crucial in modern embedded applications. The 8XC251SB and 8XC251SQ models, for instance, come equipped with multiple I/O ports that allow for interfacing with other devices and systems, enhancing their functionality in various environments.

The memory architecture of the 8XC251 devices is noteworthy, featuring on-chip ROM, RAM, and EEPROM. The on-chip memory allows for fast access times, which is essential for executing programs efficiently. Moreover, the EEPROM serves as non-volatile memory, enabling the storage of configuration settings and important data that must be retained even when power is lost.

In terms of operating voltage, the 8XC251 devices are designed to operate in a wide range, typically between 4.0V and 6.0V. This flexibility makes them suitable for battery-powered applications, where energy efficiency is critical. The power management features, including reduced power modes, further enhance their suitability for portable devices.

Lastly, the 8XC251 series is supported by a wide range of development tools and resources, allowing engineers and developers to streamline the development process. This support, combined with the microcontrollers' robust features, makes the Intel 8XC251 family a reliable choice for various embedded applications, such as industrial automation, automotive systems, and consumer electronics.

Overall, the Intel 8XC251SB, 8XC251SQ, 8XC251SA, and 8XC251SP deliver high performance, versatility, and ease of use, making them a preferred choice for embedded system designers looking to develop efficient and effective solutions.
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